Only send WM_TAKE_FOCUS when the client supports it in the protocols atom

Fixes launching xterm, for example

include/client.h

@@ -31,6 +31,12 @@ void client_remove_from_container(xcb_connection_t *conn, Client *client,
  */
 void client_warp_pointer_into(xcb_connection_t *conn, Client *client);
 
+/**
+ * Returns true if the client supports the given protocol atom (like WM_DELETE_WINDOW)
+ *
+ */
+bool client_supports_protocol(xcb_connection_t *conn, Client *client, xcb_atom_t atom);
+
 /**
  * Kills the given window using WM_DELETE_WINDOW or xcb_kill_window
  *

include/data.h

@@ -444,6 +444,9 @@ struct Client {
          * one. Therefore, this flag is set when reparenting. */
         bool awaiting_useless_unmap;
 
+        /* Whether the client needs WM_TAKE_FOCUS */
+        bool needs_take_focus;
+
         /* XCB contexts */
         xcb_window_t frame;             /**< Our window: The frame around the
                                          * client */